Water-emulsifiable metallic paste pigments



Patented Feb. 26, 1952 WATER-EMULSIFIABLE METALLIC PASTE PIGMENTS Wayne B. Roberts, Mount Lebanon, Pa., assignor to Aluminum Company of America, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing. Application November 29, 1949,

Serial No. 130,069

7 Claims. 1

This invention relates in general to -wateremulsifiable, paste pigment formulations, and in particular to such formulations in which the pigment portion is composed of metallic flakes. The invention is primarily concerned with the provision of stable, water-emulsifi'able, metallic paste pigments suitable for admixture with water in the manufacture of metallic water paints, inks, and similar coating materials. Although aluminum flakes have been contemplated as the preferred metallic pigment portion of the wateremulsifiable, metallic paste pigment formula-' tions, other'metals and their alloys may be substituted therefor.

I have discovered that known water-emulsifiable, metallic paste pigment formulations can be substantially improvedin their surface adherence and binding characteristics through the addition of one or more substantially water-free, water-soluble carbohydrates, without affecting the properties of the metallic paste pigment formulations expressed in terms of their pasteretaining consistency and freedom from ag lonm. erate formation under storage conditions sealed against atmosphere.

It is a primary object of the present invention to provide a stable, water-emulsifiable, metallic paste pigment that is characterized by freedom from hardeningten'dencies and agglom'erate formation under storage'conditions which exclude the atmosphere.

Another object of the invention is to provide a stable, water-emulsifiable, metallic paste pigment having improved adherence characteristics.

A further object of the invention is to provide a metallic paste pigment composition that is stable in storage, sealed against atmosphere,- and only requires admixture with water and stirring to produce 'a water paint coating materialcharacterized by good adherence on surfaces to which it has been applied.

Another object of the invention is to provide an aluminum paste pigment formulation stable in. storage, and useful as a mold wash in contact with molten ferrousmetals and alloys.

Other objects and advantages will present themselves to those skilled in the art to Whichin water-emulsifiable paste form that responds favorably to packaging and storage, excludingltheatmosphere, without developing pressure orhardening. Metallic pastes exhibiting. these favorable characteristics have been described and claimed in U. S. applications, Serial No. 43,551, filed August 10, 1948, and Serial No. 61,118, filed November 19, 1948, in both of whichIam a coinventor with Robert I. Wray.

The water-emulsifiable, paste formulations in question referred to in the abovezapplications are generally characterized intheir composition as comprising metallic flake, mineral spirits, .or.other. suitable hydrocarbons, at least one grease or lubricant selected from the group consisting .of palmitic, stearic, oleic and ricinoleic acid, commercial tall oil, and an emulsifier, with or. without the addition of casein as a binder.

By tall oil is meant the commercial 'byproduct from the digestion of wood pulp, which normally .contains from about 40 to 55 per cent rosin acids, from about 40 to 55 per cent fatty acids, andfrom about 5 to 10 per cent unsaponifiable material, such as sterols, higher alcohols, hydrocarbons, and the like.

Emulsifiers that have been successfully employed in water-emulsifiable, metallic .paste pigment formulations containing casein as a binder are definable in terms of the water-soluble, soapforming alkalis, selected from the group. consisting of the carbonates of sodium, the borates of sodium, morpholine, the ethanolamines and isopropanolamines, which are capable of combining with the fatty acids, and the other organic acids present on the pigment and in the tall oil, to produce efiective emulsifying agents when the paste .pigmentformulations are mixed withwater.

The water-soluble, soap-forming amino compounds selected from the group consisting of. 2- amino-l-butanol, 2-amino-2-methyl-l-propano1, 2 amino 2 methyl 1,3 propanediol, the iso-- propanolamines, the ethanolamines, morpholine and mono-n-butyl. amine may be substituted for the above stated water-soluble, soap-forming. alkalis in metallic paste formulations in. which the casein binder has been omitted.

The tall oil constituent of the water-miscible. paste formulations serves to some degree as a;

binder .in water paints prepared therefrom.

Small amounts ofv casein, in those formulationsv including one or more emulsifiers selected from. the above: named water-soluble, soap-forming. alkalis, also effect abinding action inthe finalv water paint films. Casein, however, exhibitsv a tendency to mold, and it isv preferred to. add small amounts of an anti-mold agent, or preservative, such as the borates of sodium, the phenyl-chlorophenols, or mixtures thereof, to water-emulsifiable, metallic paste pigment formulations containing casein.

I have discovered that the binding and adhesion characteristics of water paints made from stable, metallic paste formulation of the type above referred to can be materially improved through the addition of one or more substantially water-free, water-soluble carbohydrates without afiecting the stability of the paste compositions during storage, excluding the atmosphere. One or more of the substantially water-free carbohydrates represented by starch, sucrose, dextrose, maltose, lactose, levulose, and equivalent Watersoluble, substantially water-free carbohydrates can be readily incorporated in the paste formulations, preferably in a final mixing step before packaging of the same, without in any way introducing deleterious properties in the paste formulations.

Other addition agents in the form of small amount of free soap, or sodium stearate, have been found to accelerate the dispersibility of the paste pigments in water, and particularly water at room temperature. The further addition of a small amount of a water-soluble silicate, such as one of the alkali metal silicates, has also been foundto act as an inhibitor against the generation of gas within sealed containers of the paste formulations. For this purpose I prefer to use sodium disilicate.

No attempt is made to explain the precise chemical phenomena that may take place in the water-emulsifiable, metallic paste formulations or compositions forming the basis of this invention. The theory is advanced, however, that the water-soluble, soap-forming alkalis, and the water-soluble, soap-forming amino compounds, serving as emulsifiers in the paste compositions of the invention, react and/or combine with free or available fatty acid or acids, or mixtures thereof, as well as with the rosin acids, and/or other organic acids present on the metal flakes, in solution, or dispersed in the volatile hydrocarbon and/or associated with the tall oil, to form watersoluble soaps during the subsequent admixture of the paste pigments with water. Regardless of the exact chemistry involved, the water-emulsifiable,-metallic paste pigment formulations, falling within the scope of the invention are stable and free from any tendency to harden under storage conditions which exclude free access to atmosphere and moisture.

The final water-emulsifiable paste pigment formulations of the invention are not emulsions as initially formed and are kept as free from water as commercially practicable. However, small amounts of combined water, water of crystallization, and small amounts of sorb'ed water, may be tolerated in the paste pigment formulations providing the teaching and practice of the invention is followed.

Since the water-emulsifiable paste pigments of the invention are metallic in nature, water mixed paints made therefrom have significant value as mold Washes. Water paints made from Wateremulsifiable paste pigment formulations, in which the metallic portion is aluminum flake, have proved significantly successful as mold washes for hot cast iron or steel molds, in the casting of ferrous metals, in which case the improved adherence exhibited by metallic paints made from the paste formulations of the invention reduced the surface scab formations on the finished ferrous castings.

The following examples of water-miscible, metallic paste pigment formulations responding to the teaching of the invention were prepared to a standard formula by mixing 605 grams of metallic flake, mineral spirits and a small amount of a fatty acid or mixtures thereof, with 212 grams of tall oil, of which up to 10 per cent may be resinous materials, such as ester gum, 91 grams of a water-soluble, soap-forming emulsifier, of which 45 to per cent may be casein binder, 2 to 10 per centmay be a preservative, 0.1 to 5 per cent may be an inhibitor, 5 to 13 per cent may be free soap, and 652 grams of a substantially water-free, water-soluble carbohydrate, the total weight of the entire formulation in each case being 1560 grams. In the event casein is present in the paste formulation, it is preferred to also include the preservative, inhibitor and free soap within the ranges stated above.

Example I A water-emulsifiable, aluminum paste pigment formulation was prepared in the above stated proportions by a single mixing operation, and on conversion to percentage composition by Weight, the paste formulation comprised 30.5 per cent aluminum flake, 7.72 per cent mineral spirits, 0.58 per cent stearic acid, as determined in the initial aluminum paste cake containing mineral spirits, 13.7 per cent tall oil, 3.7 per cent casein, 0.7 per cent sodium carbonate, 0.56 per cent sodium bicarbonate, 0.362 per cent borax, 0.415 per cent sodium stearate, or soap, 0.063 per cent sodium silicate, and 41.7 per cent starch. The paste formulation exhibited good stability following several months storage in sealed containers, retaining its original paste consistency without any evidence of hardening, and was free from aglomerates. When mixed with water atroom temperature, as well as with hot water between to F., in amounts of 6 grams of paste to 25 cc. water, the paste readily emulsified and dispersed in the water to form a free flowing water paint that was brushed on paper and metal panels with good results, as measured in terms of paint film adhesion and hiding power. When employed as a mold wash in the casting of steel ingots, the water paint film made by employing the pigment formulation of this example exhibited adhesion characteristic superior to those of a similar paste composition without the carbohydrate starch addition.

Emample II A similarly prepared paste pigment, in which the starch was replaced in equal amount by sucrose, preferably powdered granulated sugar, gave comparable results to that of Example I.

Example III amazes *in their characteris'ticsratotthosecoftExamplesi I :tandi II.

--iEfcample TI'V t'flai's example wvas prepared'under' the? general formula" expressed in tithe :previousiexam'ples: and --its:'compositionrbyn weight was -'30..5 per 'cent salu- ;minum'.-tfiake, 7.7211161" cents-mineral:zspirits,"0.58

per cent mixture of stearicrandpalmitioacids, -1-3I7 per cent .ta1lcoil, 3:98" per "cent casein, .1.'73

p'erircent mixture of isopropanolamines,: 0.03 per .cent "sodium" silicate, 0.06 per: cent? sodium 'Stearategor soap, and 41.7*pericent'starch. .The' paste ret'ainedi'its consistency on 'sealedf storage and 'wasireadilyi emulsified in hot'water; at tempera- .tu'res betwe'en 130 to:150' F., to form satisfactory water type-paints.

I "Example V iLThis example. ;of '.a"1water;-miscible ipaste'; for- :mulation falling:.withinthetconceptrof the inventinnvwas made from --an winitial aluminum gfiake ipaste; cake which was produced using 2a monv. lea'iling :type lubricant, specifically oleic acid. tThacompositiombyiweight of this paste was 30.78

:per centaaluminum flake, 7.72'pericent'mineral spirits,- 0.3: pericenttoleic acid, 13.7' percent: tall "oil, .58 per scent '2;amino-2 methyl-1=propanol -and-;41.'7 per centstarch. iThe paste formulationtretainediits consistencyand remained stable son'zstorageidnfsealed containers. W ateri'paint madeitherefrom brushed outsatisfactorily producing a "typical 1 metallic i aluminum :surface,

with slightly" better dispersion and hiding power exhibite'dt'wh'en the" paste formulation'was mixed with wateratroom temperature, asidistinguished from'hotiwater.

Example VI water,,.and .bru'sh outs ofthe waterpairitsexhib'ited good adherence, ;hiding ...power, -metallic gloss and reflectivity.

"Example VII A water-emulsifiable, copper paste pigment formulation was-preparediinv accordance with the invention to a composition by wei ht, 31.5 per cent copper fiake,6.l5per cent mineral spirits, 1.15 per cent stearic acid, as'determined in the initial copper. .apaste tcake l-co'ntaining mineral spirits, .13.? per cent tall --oil, 3.7 per .cent

casein, 0.'7,per cent sodium carbonate, 0.56 per I cent-sodium bicarbonate,""0.362.per cent borax,

present as an anti-mold fagent, 10.063 percent si1icate,0'.415 per cent sodium stearate, or soap, and "41.7 per cent starch. 'The' paste pigment dispersed readily in hot water, as well as in Water at room temperature, in amounts of 12 grams of paste to cc. water to form free flow: ing water paints that brushed on paper and steel panels with good results to produce dried paint films exhibiting good adherence, hiding power and characteristic metallic copper coatings.

The specific amounts of the various ingredients of the water-emulsifiable, metallic paste pigment formulations given in the above examples may be varied within wide limits. A commercially practicable range for the various ingredients" thatrlhasibeen *found "economical, butnot to45 percent metallic flake cake,'or paste, containing 3 to 12 per cent mineralspirits,orequivalent volatilehydrocarbonsand 0.15 to 2 per cent ofat' least one of the fatty acids' from the group stearic,palmitic,'oleic andricinoleic acids; in admixturewith '2' tom percentof at least one water-soluble, soap-forming emulsifier, and a substantially water-free, water-soluble -carbohydrate, or mixtures'thereoffin amounts between 15" to 50 per cent, with the'balance substantially tall oil, with up'to '10 per cent of its weight resinous oil, or material such as ester'gum.

"The tall oil, and/or ester gum content of the paste 'pigmentformulations of the inventiomis preferably present' in' amounts between 9 tol26 per cent of the total weight of the:.metallic:paste pigment formulations.

Variations in the amounts: of the several-faingredients and any .particular 'JSGIBCtiOl'l of :the

equivalents in a: specific paste 1 formulation will have a' bearing"uponwhether'ihot or cold water should be employed in the final'water paint'mixture. "In' any case, hot'or'warm waterbetween and normally hastens the mixing time in any particular instance. InJthe case Of paste formulations containing the carbohydrate starch, the entire water paint mixture made therefrom may be heatedto between 150 and F.'for from 5 to '15 minutes. This tends to further'improve the adhesion of the paint films.

Commercial tall oil has been referred to and employedin'all of'the examples; with theexception of Example'VI, in which case 10 per cent by weight of the tall oil'hasibeen replaced'by ester gum, as the major portion of the liquid phase of the metallic paste pigment formulations of this invention. By the term, the balance substantially tall oil, wherever used, is meant commercial tall oil with additions of othercompatible resinous oils.

What is claimed is:

1. A water-emulsifiable,aluminum paste pigment formulation for subsequent admixture with water toform a mold *wash in ferrous casting operations, said formulation comprising 30.5 per cent aluminum flake, 7.72 per cent mineral spirits, 0.58 per cent stearic 'acid,1'3'.7'per cent tall oil,3.7 per cent casein, 0.7 percent sodium carbonate, 0.56 per cent sodium bicarbonate, 0.362 per cent bo'raxj014l5 per cent sodium stearate, 0.053 per cent sodium silicate, and 41.7 percent starch, said formulation being characterized "by its paste-retainingconsistency and freedom from agglomerate formation under storage conditions sealed against atmosphere.

2. A water-emu'lsifiable, metallic paste pigment formulation comprising 23'to 45per cent metal flake, 3' to '12 percent volatilehydrocarbon,*at least one fatty acid in'amounts between 0.15"and 2per cent selected from-the group consisting of stearic, palmitic, oleic and ri'cinoleic acids, in admixture with 9 to 26 per cent tall oil, at least one water-soluble, soap-forming emulsifier in amounts between 2 to 10 per cent selected from the group consisting of carbonates of sodium, borates of sodium, the isopropanolamines, the ethanolamines and morpholine, and 45 to 85 per cent of the emulsifier present being casein, and at least one substantially water-free, watersoluble carbohydrate in amounts between 15 to 50 per cent selected from the group consisting of starch, sucrose, dextrose, maltose, lactose and levulose, said metallic paste pigment formulation being characterized by its stability, paste-retaining consistency and freedom from agglomerate formation under storage conditions sealed against atmosphere.

3. A water-emulsifiable, metallic paste pigment formulation comprising 23 to 45 per cent metal flake, 3 to 12 per cent volatile hydrocarbon, at least one fatty acid in amounts between 0.15 and 2 per cent selected from the group consisting of stearic, palmitic, oleic and ricinoleic acids,

in admixture with 9 to 26 per cent tall oil, at

least one water-soluble, soap-forming emulsifier irLamounts between 2 to per cent selected from the group consisting of amino compounds 2-amino l butanol, 2-amino-2-methyl-l-propanol, 2-amino-2-methyl-1,3-propanediol, the isopropanolamines, the ethanolamines, morpholine and mono-n-butyl amine, and atleast one substantially water-free, water-soluble carbohydrate in amounts between to 50 per cent selected from the group consisting of starch, sucrose, dextrose, maltose, lactose and levulose, said metallic paste pigment formulation being characterized by its stability, paste-retaining consistency and freedom from agglomerate formation under storage conditions sealed against atmosphere.

4. A water-emulsifiable, aluminum paste pigment formulation comprising 23 to 45 per cent aluminum flake, 3 to 12 per cent volatile hydrocarbon, at least one fatty acid in amounts between 0.15 and 2 per cent selected from the group consisting of stearic, palmitic, oleic and ricinoleic acids, in admixture with 9 to 26 per cent tall oil, at least one water-soluble, soap-forming emulsifier in amounts between 2 to 10 per cent selected from the group consisting of carbonates of sodium, borates of sodium, is isopropanolamines, the ethanolamines and morpholine, and 45 to 85 per cent of the emulsifier present being casein, and at least one substantially water-free, Watersoluble carbohydrate in amounts between 15 to 56 per cent selected fromthe group consisting of starch, sucrose, dextrose, maltose, lactose and levulose, said aluminum paste pigment formulation being characterized by its stability, pasteretaining consistency and freedom from agglomerate formation under storage conditions sealed against atmosphere.

5. A water-emulsifiable, aluminum paste pigment formulation comprising 23 to 45 per cent aluminum flake, 3 to 12 per cent volatile hydrocarbon, at least one fatty acid in amounts between 0.15 and 2 per cent selected from the group consisting of stearic, palmitic, oleic and ricinoleic acids, in admixture with 9 to 26 per cent tall oil, at least one water-soluble, soapforming emulsifier in amounts between 2 to 10 per cent selected from the group consisting of amino compounds 2-arnino-1-butanol, Z-amino- Z-methyl-l-propanol, 2-amino-2-methyl-1,3- prop-anediol, the isopropanolamines, the ethanolamines, morpholine and mono-n-butyl amine,

and at least onezsubstantially water-free, watersoluble carbohydrate in amounts between 15 to 50 per cent selected from the group consisting of starch, sucrose, dextrose, maltose, lactose and levulose, said aluminum paste pigment formulation being characterized by its stability, pasteretaining consistency and freedom from agglomerate formation under storage conditions sealed against atmosphere.

6. A water-emulsifiable, aluminum paste pigment formulation comprising a mixture of 23 to per cent aluminum flake, 3 to 12 per cent volatile hydrocarbon, at least one fatty acid in amounts between 0.15 and 2 per cent selected from the group consisting of carbonates of sodium, borates of sodium, the isopropanolamines, from the group consisting of stearic, palmitic, oleic and ricinoleic acids, .at least one Watersoluble, soap-forming emulsifier in amounts between 2 to 1'0 per cent selected from the group consisting of carbonates of sodium, borates of sodium, the isopropanolamines, the ethanolamines and morpholine, of which 45 to 85 per cent of the emulsifier present is casein binder, 2 to 10 per cent 'of the emulsifier present is borax preservative, 0.1 to 5 per cent of the emulsifier present is water-soluble silicate inhibitor and 5 to 13 per cent of the emulsifier present is free soap, at least one substantially Water-free, Water-soluble carbohydrate in amounts between 15 to per cent selected from the group consisting of starch, sucrose, dextrose, maltose, lactose and levulose, and the balance substantially tall 011, said aluminum paste pigment formulation being characterized by its stability, paste-retaining consistency and freedom from agglomerate formation under storage conditions sealed against atmosphere.

7. A water-emulsifiable, cop-per paste pigment formulation for subsequent admixture with Water to form a copper base coating paint, said formulation comprising 31.5 per cent copper flake, 6.15 per cent mineral spirits, 1.15 per cent stearic acid, 13.7 per cent tall oil, 3.? per cent casein, 0.7 per cent sodium carbonate, 0.56 per cent sodium bicarbonate, 0.362 per cent borax, 0.063 per cent silicate, 0.415 per cent sodium stearate, and 41.7 per cent starch, said formulation being characterized by its paste-retaining consistency and freedom from agglomerate formation under storage conditions sealed against atmosphere.

WAYNE B. ROBERTS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Zavaleta Sept. 28, 1948 

2. A WATER-EMULSIFIABLE, METALLIC PASTE PIGMENT FORMULATION COMPRISING 23 TO 45 PER CENT METAL FLAKE, 3 TO 12 PER CENT VOLATILE HYDROCARBON, AT LEAST ONE FATTY ACID IN AMOUNTS BETWEEN 0.15 AND 2 PER CENT SELECTED FROM THE GROUP CONSISTING OF STEARIC, PALMITIC, OLEIC AND RICINOLEIC ACIDS, IN ADMIXTURE WITH 9 TO 26 PER CENT TALL OIL, AT LEAST ONE WATER-SOLUBLE, SOAP-FORMING EMULSIFIER IN AMOUNTS BETWEEN 2 TO 10 PER CENT SELECTED FROM THE GROUP CONSISTING OF CARBONATES OF SODIUM, BORATES OF SODIUM, THE ISOPROPANOLAMINES, THE ETHANOLAMINES AND MORPHOLINE, AND 45 TO 85 PER CENT OF THE EMULSIFIER PRESENT BEING CASEIN, AND AT LEAST ONE SUBSTANTIALLY WATER-FREE, WATERSOLUBLE CARBOHYDRATE IN AMOUNTS BETWEEN 15 TO 50 PER CENT SELECTED FROM THE GROUP CONSISTING OF STARCH, SUCROSE, DEXTROSE, MALTOSE, LACTOSE AND LEVULOSE, SAID METALLIC PASTE PIGMENT FORMULATION BEING CHARACTERIZED BY ITS STABILITY, PASTE-RETAINING CONSISTENCY AND FREEDEOM FROM AGGLOMERATE FORMATION UNDER STORAGE CONDITIONS SEALED AGAINST ATMOSPHERE.
 3. A WATER-EMULSIFIABLE, METALLIC PASTE PIGMENT FORMULATION COMPRISING 23 TO 45 PER CENT METAL FLAKE, 3 TO 12 PER CENT VOLATILE HYDROCARBON, AT LEAST ONE FATTY ACID IN AMOUNTS BETWEEN 0.15 AND 2 PER CENT SELECTED FROM THE GROUP CONSISTING OF STEARIC, PALMITIC, OLEIC AND RICINOLEIC ACIDS, IN ADMIXTURE WITH 9 TO 26 PER CENT ALL OIL, AT LEAST ONE WATER-SOLUBLE, SOAP-FORMING EMULSIFIER IN AMOUNTS BETWEEN 2 TO 10 PER CENT SELECTED FROM THE GROUP CONSISTING OF AMINO-COMPOUNDS 2-AMINO-1-BUTANOL, 2-AMINO-2-METHYL-1-PROPANOL, 2-AMINO-2-METHYL-1,3-PROPANEDIOL, THE ISOPROPANOLAMINES, THE ETHANOLAMINES, MORPHOLINE AND MONO-N-BUTYL AMINE, AND AT LEAST ONE SUBSTANTIALLY WATER-FREE, WATER-SOLUBLE CARBOHYDRATE IN AMOUNTS BETWEEN 15 TO 50 PER CENT SELECTED FROM THE GROUP CONSISTING OF STARCH SUCROSE, DEXTROSE, MALTOSE, LACTOSE AND LEVULOSE SAID METALLIC PASTE PIGMENT FORMULATION BEING CHARACTERIZED BY ITS STABILITY, PASTE-RETAINING CONSISTENCY AND FREEDOM AGGLOMERATE FORMATION UNDER STORAGE CONDITIONS SEALED AGAINST ATMOSPHERE. 